Nickel electroplating and electrolytes therefor

ABSTRACT

IN ACCORDANCE WITH CERTAIN OF ITS ASPECTS, THE NOVEL PROCESS OF THIS INVENTION FOR ELECTROPLATING NICKEL MAY COMPRISE ELECTRODEPOSITING NICKEL FROM AN AQUEOUS NICKEL ELECTROPLATING BATH CONTAINING (A) AS A FIRST PRIMARY BRIGHTENER AN EFFECTIVE AMOUNT OF A WATER-SOLUBLE ACETYLENIC COMPOUND, AND (B) AS A SECOND PROMARY BRIGHTENER, AN EFFECTIVE AMOUNT OF A COMPOUND HAVING AS CATION:   A-CH2-(+)N&lt;(-)(-R*A)   WHEREIN   N&lt;(-)   IS A PYRIDINE, QUINOLINE, OR ISOQUINOLINE NUCLEUS; A IS 0-5; A IS-CX=CHX OR C$CH; X IS AN ACTIVE HALIDE; AND R* IS A SUBSTITUTENT SELECTED FROM THE GROUP CONSISTING OF ALKYL, PREFERABLY HAVING 1-4 CARBON ATOMS, HYDROXY-ALKYL PREFERABLY HAVING 1-4 CARBON ATOMS, HALOGEN, ALKOXY, CARBOXYL, CARBALKOXY, ACETYL, BENZYL, SULFO, CARBOXAMIDO, AND CYANO.

United States Patent US. Cl. 20449 13 Claims ABSTRACT OF THE DISCLOSUREIn accordance with certain of its aspects, the novel process of thisinvention for electroplating nickel may comprise electrodepositingnickel from an aqueous nickel electroplating bath containing (a) as afirst primary brightener an effective amount of a Water-solubleacetylenic compound, and (b) as a second primary brightener, aneffective amount of a compound having as cation:

is a pyridine, quinoline, or isoquinoline nucleus; a is 0-5; A is-CX=CHX or -CECH; X is an active halide; and R* is a substituentselected from the group consisting of alkyl, preferably having l-4carbon atoms, hydroxy-alkyl preferably having 1-4 carbon atoms, halogen,alkoxy, carboxyl, carbalkoxy, acetyl, benzyl, sulfo, carboxamido, andcyano.

wherein This application is a continuation-in-part application of U5.patent application Ser. No. 587,393, filed Oct. 18, 1966, now abandoned.

The present invention relates to a process for nickel plating. Moreparticularly it relates to a process for bright nickel platingcharacterized by outstanding coverage in low current density areas.

It is an object of this invention to provide a process for nickelplating and in particular one which is characterized by outstandingcoverage in low current density areas. Other objects will be apparent tothose skilled in the art on inspection of the following description.

In accordance with certain of its aspects, the novel process of thisinvention for electroplating nickel may comprise electrodepositingnickel from an aqueous nickel electroplating bath containing (a) as afirst primary brightener an effective amount of a water-solubleacetyleriic compound, and (b) as a second primary brightener, aneffective amount of a compound having as cation:

A is CX=CI-IX or --CECH; X is an active halide; and -R* is a substituentselected from the group consistwherein 3,677,912 Patented July 18, 1972ing of alkyl, preferably, having 1-4 carbon atoms, hydroxy-alkylpreferably having 1-4 carbon atoms, halogen, alkoxy, carboxyl,carbalkoxy, acetyl, benzyl, sulfo, carboxarnido, and cyano.

The basis metals which may be electroplated in accordance with theprocess of this invention may include copper or copper alloys; ferrousmetals including steel, iron, etc.; zinc and its alloys includingzinc-base die castings; nickel; etc. Preferably the basis metal may beara plate of copper and of semi-bright nickel before being subjected tothe process of this invention.

The primary brighteners of the present invention may be useful with e.g.Watts type baths, High Chloride type baths, and Sulfamate type baths,including those typified by the illustrative baths of Tables I, II; andIII.

TABLE I Watts-type baths Nickel sulfate 200-400 g./l. Nickel chloride30-75 g./l. Boric acid 30-50 g./l. Temperature 30 C.-65 C. pH 3.5-5.0electrometric.

With agitation (either mechanical, air, or solution circulation bypumping).

TABLE II High chloride baths Nickel chloride -300 g./l. aNickel sulfate40-225 -g./1. Boric acid 30-50 g./l. Temperature 30 C.-65 C. pH 3.5-5.0electrometric.

With agitation (either mechanical, air, or solution circulation bypumping).

TABLE III Sulfamate-type baths Nickel sulfamate 330-600 g./1. Nickelchloride 15-60 g./l. Boric acid 35-55 g./l. Temperature 30-55 C. pH3.5-5.0 electrometric.

With agitation (either mechanical, air, or solution circulation bypumping).

Other nickel plating baths include those containing, as a source ofnickel, nickel fluoborate with nickel chloride, nickel sulfamate withnickel chloride, etc. In the above tables, the nickel chloride ismetered as the hexahydrate NiCl -6H O, and the nickel sulfate as theheptahydrate NiSO -7H O. Other compounds e.g. boric acid are metered onan anhydrous basis.

The plating conditions for electrodeposition from the aforementionedbaths may for example include temperature of 30 C.-65 C., pH of 3.5-5electrometric, and preferably 3.8-4.5, cathode current density of 1-10amps. per sq. dm. Typical preferred current density of the baths ofTable I may be 4-6 amps. per sq. dm. Agitation may be preferred whileplating.

It is a particular feature of the process of this invention that itpermits outstanding results when a Wattstype bath is employed.

The first primary brightener which may be employed in which each of Rand R may be substituents selected from the group consisting ofhydrogen, alkyl, alkenyl, alkynyl, hydroxy-substituted andalkoxy-substituted alkyl, alkenyl, and alkynyl groups, and R and R maytogether he a carbonyl oxygen; R may be a substituent of the groupconsisting of hydrogen, halogen, alkyl, alkenyl, alkynyl,hydroxy-substituted and alkoxy-substituted alkenyl and alkynyl groups,and substituted-alkyl groups having the formula in which each of R and Rmay be substituents selected from the group consisting of hydrogen,alkyl, alkenyl, alkynyl, and hydroxy-substituted and alkoxy-substitutedalkyl, alkenyl, and alkynyl groups, and when R and R together arecarbonyl oxygen, R may be an aryl group, including hydroxy and alkoxyand alkyl-substituted aryl; each of R, and R, may be substituentsselected from the group consisting of hydroxy, alkoxy,carboxy-substituted alkoxy, formoxy, alkanoxy, halogen and polyoxygroups and R,, may also be an amino group including alkyl and arylsubstituted amino group wnen R and R together form a carbonyl oxygen andR is an aryl group. Where R is a substituted-alkyl group having theabove-illustrated formula, the acetylenic compound may be termed anu,a'- disubstituted acetylenic compounds, since both carbon atomsvicinal to the same acetylenic bond contain either the same or adilferent functional group.

The compounds listed in Table IV are illustrative of the water-solubleacetylenic compounds which may be used in practice of the process ofthis invent-ion.

TABLE IV 2-butyne-l,4-diol 1,4-di-(3-hydroxyethoxy)-2-butynel-(fihydroxyethoxy)-2-butyne-4-ol 1,4-diacetoxy-2-butyne3-butyne-l,2-diol I I 3-methyl-1-butyne-3-ol 3-methyl-lpentyn-3-olZ-propyn-Lol 2,5-dimethyl-1-octen-3-yn-5-ol 3-methy1-1-nonyn-3-ol2,4-hexadiyne-l,6-diol 1-methoxy-2-propyne3-methoxy-3-methyl-4,6-heptadiyne 3-ethoxy-3,S,7-trimethyl-1-octynel-formoxy-Z-propyne l-acetoxy-Z-propyne 3-methyl-1-nonyn-3-yl-acetatephenyl-propiolamide phenyl-propiol-N-phenylamidephenyl-propiol-N,N'-dimethylamide 3-methyl-1-butyn-3-yl acetate v 41-chlor-6-methoxy-2,4-hexadiyne 3-chloro-3-methyl-4-hexynel-bromo-Z-propyne 1 ,2-difi-hydroxyethoxy) -3 -butyne 3-(fi-hydroxy--chloropropoxy)-3-methyl-4-pentyne 3-(B- y-epoxypropoxy)-3-methy1-4-pentyne Those acetylenic compounds which may be employed inthe instant invention include those containing at least one hydroxymoiety, and most preferably those which contain two hydroxy moieties,e.g. the fl-hydroxycthyl ether of 2-butyne-l,4-diol, i.e. 1-(fi-hydroxy-ethoxy)-4-hydroxy-Z-butyne, and preferably the bis(B-hydroxy ethyl ether( of 2-butyne-l,4-diol, i.e. -I,4-bis(B-hydroxyethoxy)- Z-butyne:

The first primary brightener may be present in the bath in elfectiveamounts of 0.002 g./l.-0.S g./l., preferably 0.005 g./l.0.l0 g./l., say0.01 g./1.0.05 g./l.

The second primary brightener which may be employed in practice of thisinvention may include nitrogen heterocyclic compounds having as cationIts-9+4: Hn-A.

is a pyridine, quinoline, or isoquinoline nucleus (including such nucleiwhen substituted or unsubstituted); a is 0-5; A is CX=C-HX or C=CH; X isan active halide; R* is a substituent selected from the group consistingof alkyl preferably having 1-4 carbon atoms, hydroxyalkyl preferablyhaving 14 carbon atoms, halogen, alkoxy, carboxyl, carbal-koxy, acetyl,benzyl, sulfo, carboxamido, and

cyano.

More particularly, the second primary brightener may be a compoundwherein n/CHz-A. R,- N

wherein X is a bath-soluble, bath-compatible anion, typically bromide,chloride, iodide, fluoride, acetate, sulfate, methosulfate, ethosulfate,citrate, chloroacetate, perchlorate, etc. Preferably X may be halideincluding fluoride, chloride, bromide, and iodide. These compounds maybe readily available or may be conveniently prepared by the reactionCHa-A Ram A-cHr-x' RflDN e.g. the reaction of 2,6-dimethyl pyridine andpropargyl bromide to form 2,6-dimethyl, N-propargyl pyridinium bromide;or the reaction of pyridine and 1,2,3-trichloropropene to form1,2-dichloropropene pyridinium chloride. When A is CX=CHX and, when-X isbromo, then compound (II) will preferably be prepared by the reaction ofcompound (111) infra with bromine e.g. reaction of 2,6-dimethyl,N-propargyl pyridinium bromide with bromine to form 2,6-dimethyl,N-2,3-dibromo propenyl pyridinium bromide.

It will be apparent to those skilled-in-the-art that Formula Il mayinclude, in addition to simple pyridine, quinoline, and isoquinolinederivatives, other compounds including those formed from eg4,4'-dipyridine: such as N,N bis-Z-propynyl-4,4'-dipyridinium dibromideformed by the reaction 4,4'-dipyridine and propynyl bromide; or N,N'bis-2,3-dichloropropynyl, 4,4'-dipyridinium dichloride formed by thereaction of 4,4'-dipyridine and 2,3- dichloropropenyl chloride.

In the above Formula II when A is C=CH, the compound may be CHa-CECH X(III) In this embodiment, it is preferred that R* be alkyl orhydroxyalkyl, and a be an integer -5. When a is 2-5, there may be bothalkyl and hydroxyalkyl groups on the molecule. R* may typically bemethyl, ethyl, propyl, ipropyl, n-butyl, i-butyl, t-butyl, n-amyl,n-hexyl, n-octyl, Z-ethylhexyl, etc., hydroxymethyl, S-hydroxyethyl,gamma-hydroxypropyl, fi-dihydroxypropyl, etc.

Typical compounds which may fall within the scope of Formula III may be:

TABLE V 2,6-dimethyl, N-propargyl pyridinium bromide 3,5 -dimethyl,N-propargyl pyridinium bromide 2,4-dimethyl, N-propargyl pyridiniumbromide 3,4dimethyl, N-propargyl pyridinium bromide 2,5-dimethyl,N-propargyl pyridinium bromide 3-ethyl, 4-methyl, N-propargyl pyridiniumbromide 2,4,6-trimethyl, N-propargyl pyridinium bromideZ-fi-hydroxyethyl, N-propargyl pyridinium bromide Z-gamma-hydroxypropyl,N-propargyl pyridinium bromide 3-hydroxymethyl, N-propargyl pyridiniumbromide Z-methyl, 6-gamma-hydroxypropyl, N-propargyl pyridinium bromide2-ethyl, 4,6-di-p-hydroxyethyl, N-propargyl pyridinium bromide 2,4,6-tri-hydroxymethyl, N-propargyl pyridinium bromide The preferredcompounds may include 2,4,6-trimethyl, N-propargyl pyridinium bromideand 2,4-dimethyl, N- propargyl pyridinium bromide.

In the above Formula II when A is CX=CH.X, the compound may be CH3CX=CHXn YK In this embodiment, it is preferred that R be alkyl or halogenincluding bromine or chlorine, and that a be 0-3. These compounds mayinclude N-2,3-dihalopropenyl pyridinium halide.

Typical compounds which may fall within the scope of Formula IV mayinclude:

TABLE VI N-2,3-dibromopropeny1 2,4,6-trimethylpyridininm bromideN-2,3-dibromopropenyl 3,5-dimethylpyridinium bromideN-2,3-dibromopropenyl 4-isopropylpyridinium bromideN-2,3-dibromopropenyl 2,6-dimethylpyridinium bromideN-2,3-dibromopropeny1 Z-aminopyridinium bromide N-2,3-dibromopropenyl3-methylpyridinium bromide N-2,3-dibromopropenyl 3-cyanopyridiniumbromide N-2,3-dibromopropenyl 4-ethylpyridinium bromideN-2,3-dibromopropenyl 4-methylpyridinium bromide N-2,3-dibromopropenyl2,4-dimethylpyridinium bromide N-2,3-dibromopropenyl 2-chloropyridiniumbromide N-2,3-dibromopropenyl 2-ethylpyridinium bromideN-2,3-dibromopropeny1 Z-fi-hydroxyethylpyridinium bromideN-2,3-dibromopropenyl 2-y-hydroxypropylpyridinium bromideN-2,3-dibromopropenyl 2-methylquinolinium bromide N-2,3-dibromopropenyl2p-methoxybenzylaminopyridinium bromide N-2,3-dibromopropenylisoquinolinium bromide N-2,3-dibromopropenyl 3-sulfopyridinium bromide(Na salt) N-2,3-dibromopropenyl 3-hydroxymethylpyridinium bromideN-2,3-dibromopropenyl 2-methylpyridinium bromide N-2,3-dibromopropenyl3,4dimethylpyridinium bromide N-2,3-dibromopropenyl2,5-dimethylpyridinium bromide N-2,3 -dibromopropenyl3-ethyl-4-methylpyridinium bromide N-2,3-dibromopropenyl4-methylquinolinium bromide N-2,3-dibromopropenyl 2-aldoximopyridiniumbromide N-2,3-dibromopropenyl 2,6-diaminopyridinium bromide1,2-dichloropropenyl pyridinium chloride 1,2-dichloropropenyl pyridiniumiodide 1,2-dichloropropenyl 3,4-dimethylpyridinium iodide1,2-dichloropropenyl 4-methylpyridinium iodide 1,2-dichloropropenyl2-methylpyridinium iodide 1,2-dichloropropenyl 3,5-dimethylpyridiniumiodide The second primary brightener may be present in the bath ineifective amount of 0.002 g./l.0.01 g./l., preferably 0.002 g./l.-0.05g./l., say 0.01 g./l. Preferably the total amount of primary brightener,including the first and second primary brightener, may be 0.004 g./l.0.6g./l., more preferably 0.007 g./l.-0.l5 g./l., say 0.02 g./l.

The preferred nickel electroplating baths of this invention may includesecondary brighteners, present in typical amounts of 1 g./l.75 g./l.,preferably 1 g./l.-20 g./l., such as the sulfo-oxygen compounds typicalof which may be saccharin and sodium benzene monosulfonate. The lattersecondary brightener may be preferred because of its higher degree ofzinc-tolerance, i.e. its ability to tolerate higher concentrations ofzinc as contaminant without giving striations in the low current densityareas. In high chloride baths, it may be preferred to use saccharin orthe sodium salt of sulfonated dibenzothiophene dioxide. Naphthalenesulfonates may be found to be of little or no efiectivity in the processof this invention.

Secondary auxiliary brighteners, typically present in amount of 2g./l.30 g./l., preferably 2 g./l.-10 g./l., say 4 g./l., may includeunsaturated hydrocarbon sulfonates such as sodium 3-chloro-2-butenesulfonate; sodium 2- propen-l-sulfonate; sodium1-phenylether-2-sulfonate; sodium 3-methyl-1-buten-3-ol-l-sulfonate;sodium 3-hydroxy-l-propen-l-sulfonate; etc.

Plating of nickel by the novel process of this invention permitsattainment of a brilliant ductile, highly leveled deposit of brightnickel over a wide range of current density. In particular cases, suchas when saccharin is used as the secondary brightener, coverage in thelow current density region is substantially increased. Generally theremay be an improvement in the rate of brightening and the elimination ofbuild-up of satiny-to-dull micronodular deposits in low current densityareas.

For purpose of providing those skilled-in-the-art with a betterunderstanding of this invention, the following examples are set forthwherein all parts are parts by weight unless otherwise specified.

In these examples, the Watts Bath contained:

8 The Acetylenic Primary Brighteners used were:

TABLE VII Example Additives Amt., gJl.

(A) Z-butyne 1,4-diol 8 0. 01 (B) 1,4-di-(B-hydroxyethoxy)-2-butyne i1,1% (C) 3-methyl-1-butyne-3'ol B' 310 (D) 3-methyl-1-pentyne-3-ol 9 M C 001 (E) 3-methy1-l-butyne-3-(B-hydroxyethoxy) u 12: 0. 05 TheN-heterocyclic Primary Brighteners used were: TABLE VIII 0 g, 3-3; (A)N-2,3-dichloropropenyl pyridinium chloride 7 g, (B')N-2,3-dibromopropenyl-2,4,6 trimethyl pyridinium bromide 11 3'8? ((3')N-2-propynyl-2,4,6-trimethyl pyridinium bromide Z, (D')N,N'bis-2-propynyl-4,4-dipyridinium dibromide A (E')N,Nbis-2,3-dichloropropenyl-4,4' dipyridininm di- 12 B 0. 0s chlorideSi" 4 The secondary Brighteners used were: Am

a (A") Saccharin (Na salt) 1 1 09032. (B") Sodium benzene monosulfonatefix, 2-8 (C") Disodium m-benzene disulfonate (D") Sodium p-toluenesulfonate 14 8? (E") Sulfonated dibenzothiophene dioxide (Na salt) if1.0 The Secondary Auxiliary Brighteners used were: 15 C (A") Sodium3-chloro-2-butene sulfonate h g, {.105 (B) Sodium 2-propene-1-sulfonate15 I)! (C Sodium l-phenylethene-Z-sulfonate 16 0 cm The Anti-pittingAgents used were: 81', 0 (A"") Sodium lauryl sulfate B," 3 Sodiumdi-n-hexyl sulfosuccinate 17 C 01 A 0 01 In the examples, the baths usedwere Watts Baths for 2; 7.5 Examples 1-19; High Chloride Baths forExamples 20-26; 0 and Sulfamate Baths for Examples 27-34. The additives18 D 0,0 were present in the amount indicated. All runs were made 1,using highly polished brass cathodes with the cathode cur- B rentdensities averaging 5 a.s.d. at a temperature of 60 19 C. for the Wattsand Sulfamate Baths and 6 a.s.d. at a "K, 8- temperature of 65 C. forthe High Chloride Bath. In Ex 4.0 Examples 1-19 and 27-34 air agitationwas used and the A baths contained 0.2 g./l. of B"". In Examples 20-26mov- 20 7 0, ing cathode rod type of agitation was used and the bathsi1, 01 contained 0.5 g./l. of A"". The plating time was 30 mina 18 utes.To evaluate the degree of leveling the brass cathodes were scratchedbefore plating with a single pass of 4-Zero 21 2. 3-8? grit emery. 4.0B!!! 3 0 Example Additives Amt., g./1. 22 g, 0 01 1 A 0.10 A" f? n m 4.Q A'" 23 o 3.31 2 B 0 05 1 1 A" 4. 0 AZ, u! 0 A 24 (J Q01 3 o 0.01 0' 0.005 0.01 gx. g-g 25 C 0. 01 4 D 0.01 I

A1 0. 01 E" 4% A," (0) All! 4'0 2a-- B 0 0s 5 E 0.01 l I n u 0 01 A 0.01A 4 0 A 410 27 B 0,05 6 C 0.01 0 0 a. s; A 4Z0 7 2s o 0. 01 7 X, 8-5;?A1 0. 01 A" 4.0 7. 5 B 3.0

TABLEContinued Example Additives Amt, g./l.

In all of the above examples which fall within the scope of thisinvention, it was observed that the nickel plate was characterized by ahigh degree of leveling, ductility, and rate of brightening. In the caseof Example 2, the preferred embodiment, the combination of primarybrighteners gave extremely high leveling, ductility, rate ofbrightening, and substantial improvement in coverage in the low currentdensity area. Improved coverage in low current density areas may beparticularly outstanding when saccharin is used as the secondarybrightener.

EXAMPLE 35 In a Watts nickel system the following additive system wastested on a four-liter laboratory scale over a relatively long period ofelectrolysis time:

(B")sodium benzene monosulfonate (A')-sodium 3-chloro-2-butyne sulfonate(C)3-methyl-l-butyne-3-ol (B"")sodiurn di-n-hexyl sulfosuccinate Theabove system gave deposits of high luster and good rates of brighteningand leveling; ductility was acceptable and the system was very tolerantto zinc as a contaminant. Despite these good characteristics, it wasfound that on unpolished surfaces of basis metals this system had a verystrong tendency to lose luster instead of gaining luster with increasingthickness of deposit. On examination under magnification, the loss ofluster was found to be due to the very unusual and unexpected formationof closely spaced micromounds instead of a smooth highly lustrousdeposit without discontinuities. To this bath there was then addedanother primary brightener [i.e. N-2,3-dichloropropenyl pyridim'umchloride (A')] without any prior knowledge as to what the effects mightbe. The defect was immediately eliminated with all of the other goodproperties of the system being retained. If, instead of using thecombinations of primary brighteners, only nitrogen heterocyclic wereused, the system would produce an inadequate deposit luster, and ratesof brightening and leveling would be lower. The combined system turnedout to be highly successful in all respects while preserving all of theprevious advantages and without introducing any new defects.

EXAMPLE 36 In a Watts nickel system the following additive system wasinvestigated:

saccharin sodium-3-chlorobutene sulfonatel,4-di(fi-hydroxyethoxy)-2-butyne sodium di-n-hexyl sulfosuccinate Theabove system had all the desired characteristics of a bright nickelsystem except that at concentrations of 'the acetylenic primarybrightener necessary to obtain adequate luster and rates of brighteningand leveling, the low current density coverage was consideredinadequate. On adding N-2,3-dichloropr0penyl pyridinium chloride to thessytem this defect was eliminated and a highly successful processresulted. When using the N-heterocyclic without the cooperatingacetylenic brightener, the system possessed inadequate rates ofbrightening and leveling from a commercial standpoint.

EXAMPLE 37 The system formulated under Example 36 (above) was found tobe somewhat sensitive to zinc contamination when sodium allyl sulfonatewas substituted for sodium 3-chlorobutene sulfonate. On adding2-butyne-1,4-diol as an additional cooperating primary brightener, thesensitivity towards zinc contamination was remarkably reduced and ahighly successful process resulted.

It will be apparent to those skilled in the art that variousmodifications may be made to the specific embodiments herein set forthby way of example.

I claim:

1. The process for electroplating nickel which comprises electroplatingnickel from an aqueous acidic nickel electroplating bath containing (a)as a first primary brightener 0.002 gram per liter to 0.5 gram per literof at least one compound selected from the group consisting ofbutynediol and hydroxyethoxylated butynediol and (b) as a second primarybrightener, 0.002 gram per liter to 0.01 gram per liter of a compoundhaving as cation C is a pyridine, quinoline, or isoquinoline nucleus; ais 0-5; A is CX=CHX or CECH; X is an active halide; and R* is asubstituent selected from the group consisting of alkyl, hydroxyalkyl,halogen, alkoxy, carboxyl, carbalkoxy, acetyl, benzyl, sulfo,carboxamido, and cyano.

2. The process for electroplating nickel as clamied in claim 1 whereinsaid water-soluble acetylenic compound is 2-butyne-1,4-diol.

3. The process for electroplating nickel as claimed in claim 1 whereinsaid water-solubel acetylenic compound is1,4-di-(beta-hydroxyethoxy)-2-butyne.

4. The process for electroplating nickel as claimed in claim 1 whereinsaid water-soluble acetylenic compound isl-(beta-hydroxyethoxy)-4-hydroxy-2-butyne.

5. The process for electroplating nickel as claimed in claim 1 whereinsaid second primary brightener has as cation wherein claim 1 whereinsaid second primary brightener has as cation ng rLom-oiho 11x and a is0-3.

8. The process for electroplating nickel as claimed in claim 1 whereinsaid second primary brightener has as cation If -cm-ox=cnx 9. Theprocess for electroplating nickel as claimed in claim 1 wherein secondprimary brightener is N-2,3-dichloropropenyl pyridinium chloride.

10. An aqueous acidic electrolytic bath containing soluble salts for theelectrodeposition of nickel and containing 0.002 gram per liter to 0.5gram per liter of at least one compound selected from the groupconsisting of butynediol and hydroxyethoxylated butynediol and 0.002gram per liter to 0.01 gram per liter of a compound having as cationwherein is a pyridine, quinoline, or isoquinoline, nucleus; a is 0-5;

A is CX=CHX or Cz-CH; X is an actvie halide; and R* is a substituentselected from the group consisting of alkyl, hydroxyalkyl, halogen,alkoxy, carboxyl, carbalkoxy, acetyl, benzyl, sulfo, carboxamido, andcyano.

11. An aqueous electrolytic bath containing soluble salts for theelectrodeposition of nickel as claimed in claim 10 wherein saidwater-soluble acetylenic compound is 2-butyne-1,4-diol.

12. An aqueous electrolytic bath containing soluble salts for theelectrodeposition of nickel as claimed in claim 10 wherein saidwater-soluble acetylenic compound is 1,4-di(betahydroxyethoxy)-2-butyne.

13. An aqueous electrolytci bath containing soluble salts for theelectrodeposition of nickel as claimed in clami 10 wherein saidwater-soluble acetylenic compound is1-(betahydroxyethoxy)4-hydroxy-2-butyne.

References Cited UNITED STATES PATENTS 3,218,244 11/1965 Passal et a1204-49 3,054,733 9/1962 Heiling 204-49 2,315,802 4/ 1943 Lind et al.204-49 2,818,376 12/ 1957 Fonlke et a1 204-49 3,140,988 7/1964 Clauss etal. 204-49 3,206,103 1/1967 Passal 204-49 GERALD L. KAPLAN, PrimaryExaminer

